Fuel source and method of forming same from blending wastewater contaminants with biomass leftovers while cleansing wastewater

ABSTRACT

A blending of sludge, grease and/or fats extracted from wastewater with biomass leftovers to form a fuel. The biomass leftovers may be pulverulent wood charcoal, pulverulent cellulose, vegetable oil, vegetable alcohol or any combination. The sludge, grease and fats are extracted while cleansing the wastewater of contaminants. The fuel may be burned to produce heat to drive a steam turbine. The cleansed water may flow to drive a water turbine. If a current population of bacteria cannot be sustained by the amount of contaminants in fresh supplies of the wastewater alone at a particular time, the previously extracted sludge may be used to supplement to help sustain the bacteria population. Likewise, when the amount of contaminants in fresh supplies of the wastewater exceeds what is necessary for the current population of bacteria to sustain itself, such excess may be extracted for use later or blended to form the fuel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to forming fuels from a mixture ofwastewater pollutants/contaminants and biomass leftovers, preferablyduring cleansing of wastewater. The pollutants/contaminants areextracted from wastewater preferably with mechanical devices, such asgrease traps and sludge dewatering devices.

2. Discussion of Related Art

Wastewater treatment from residential sources requires the processing oforganic based sludge, grease and fats. The grease may be, for instance,in the form used vegetable cooking oils and residue from cosmeticproducts such as face creams, body oils, etc. The fats may includeanimal fats.

Conventional wastewater treatment facilities use mechanical, chemicaland biological processes to treat the organic based sludge, grease andfats. U.S. Pat. No. 6,767,464, whose contents are incorporated byreference, identifies various mechanical, chemical and biologicalprocesses employed conventionally to cleanse wastewater of contaminants.

Indeed, U.S. Pat. No. 6,767,464 recognizes that grease, fats and oilsare discharged into water treatment systems, and grease and fat trapsare sometimes employed to remove these materials. Costs are incurred atregular intervals for the removal and disposal of grease and fats fromthese traps, especially by users processing food. For the treatment ofgrease, fats and oils, the enzyme lipases, lipase releasing bacteria orbacteria capable of breaking down grease and fats could be used. Thesewould convert the grease, fats and oils to glycerine, fatty acids, mono-and diglycerides. The breakdown products can then be diverted to theaerobic or anaerobic regions of the waste water treatment system, andcan perform as an additional source of electron donor or carbon fornitrification or denitrification.

U.S. Pat. No. 6,709,593, whose contents are incorporated by reference,notes that the sludge is conventionally dewatered in a mechanicaldewatering device, e.g., a filter press or decanter centrifuge, and thedewatered sludge is sent for final disposal.

The present inventor notes that the extraction of pollutants orcontaminants from wastewater with mechanical processes, in contrast tochemical or biological processes, is a relatively inexpensive way togather such contaminants, although chemical and biological processes arestill necessary to cleanse the wastewater of toxic levels of thecontaminants. Conventional wastewater treatment systems call fordisposal of the mechanically extracted contaminants or for furtherchemical or biological processing of them. Disposal may, for instance,be at a landfill or in a natural body of water such as the ocean. Suchdisposal, obviously, is environmentally undesirable and generallyentails paying a tipping fee to the operator of the disposal site orbarge.

There are over 350 species of oleaginous, or oil-producing plants andthousands of sub-species. Two types of oil presses are used in bothsmall and large scale vegetable oil processing. The most common type ofoil press is the screw press. This press uses a large scale diameterscrew inside a metal housing. The oil seed is fed into the top of thepress and falls into the churning screw. As the seed is churned into amash by turning threads of the screw, the oil is squeezed from the meal,or cake. The protein cake from the oilseed oozes from the side of thepress and the vegetable oil dribbles from the bottom of the press.

Screw presses are available in sizes ranging from table-top models thatproduce 8 kilograms of seed per hour (2 liters of oil) to industrialmodels which can produce 4,000 kilograms of oil per day. Screw pressesare available in electrical and Diesel powered models. Screw pressestend to be slow. A ram press is more efficient oil press design. Thispress uses a hydraulic piston inside of a cylinder to crush the oilseed.Ram presses can be powered by hand, by an electric motor, or by a Dieselengine.

After a vegetable oil is pressed, it is left to settle for a few days inhorizontal settling tank. The vegetable gums and pieces of meal cakesettle to the bottom of the tank. If it is to be used as a fuel, itshould be pumped through a series of filters. Usually it is a four stageprocess, starting with 150 micron mash, then 70, then 25 and lastly a 10micron fuel filter.

An ester is a hydrocarbon chain that, for certain compounds such asalcohol or amine, will bond with another molecule. A vegetable oilmolecule is made of three esters attached to a molecule of glycerin.Vegetable oil is called a triglyceride. Vegetable oil is also calledglycerol esters. About 20% of a vegetable oil molecule is glycerin.Glycerin makes vegetable oil thick and sticky. To transform vegetableoil into fuel, vegetable oil must go through the process oftransesterification.

It would be preferable to find a use for the mechanically extractedcontaminants that avoided the necessity to either dispose of them orfurther chemically or biologically treat them to render them non-toxic.Indeed, it would preferable to transform them into an energy sourcewhile purifying or cleansing wastewater.

SUMMARY OF THE INVENTION

One aspect of the invention relates to the addition of an additive torender extracted wastewater contaminants (domestic sludge, grease, fats)useful as a fuel source. The additive is preferably biomass leftoverssuch as pulverulent wood charcoal, pulverulent sawdust or other types ofpulverulent wood or cellulosic based materials, such as from biomass. Bypulverulent, the intent is to cover powder or fibrous forms.

Preferably, a sufficient quantify of the biomass leftovers is added tothe mixture of the mechanically extracted wastewater contaminants toallow pressure from a press to be apply to form an ingot from thecombination of mixture and additive. The ingot may be burned as a fuelsource. If desired, lavender or other scents may be added to thecontaminants after their mechanical extraction to neutralize theirodors.

A further aspect of the invention concerns forming a source of energywhile cleansing wastewater of contaminants. The source of energy isformed by blending extracted grease and/or fats, extracted dried sludgeand leftover biomass. The grease and sludge are separately extractedfrom the waste water. The biomass leftovers may be pulverulent woodcharcoal, pulverulent cellulose, vegetable oil, vegetable alcohol, orany combination thereof. Vegetable alcohol refers to ethanol alcohol,methanol alcohol, a combination of each, or other forms of alcoholderived from vegetable oil after undergoing transesterification.

Another aspect of the invention concerns compensating for fluctuationsin demand for wastewater treatment by extracting sludge during timeswhen that amount of sludge in fresh supplies of wastewater exceeds thatnecessary to sustain current population levels of bacteria in a waterpurifying region of the invention so as to either reuse the sludge lateror blend it into a fuel. The sludge is returned during times when theamount of sludge in fresh supplies of wastewater is insufficient tosustain the current population levels of the bacteria in the waterpurifying region.

BRIEF DESCRIPTION OF THE DRAWING

The drawing is a schematic representation of wastewater purification,blending of extracted contaminants from the wastewater with leftoverbiomass to form a fuel mixture, and electricity generation from theturning of a water turbine with purified wastewater and from the turningof a steam generator from generating steam through the burning of theblended fuel mixture.

DETAILED DESCRIPTION OF THE INVENTION

The drawing shows a wastewater treatment and energy production system.It may be useful to consider the system to be subdivided into regions.The regions include an entry region, a water purifying region, a sludgedrying region, a blending region, power generation regions, and adischarge region. The entry region includes a lifting pump 10 that pumpswastewater to a desired level within the water purifying region, such aswithin a basin. Mechanical cleansing equipment, such as a grease trap20, is used to trap grease and/or fats in the wastewater. The trappedgrease and/or fats are pumped or otherwise discharged to a grease tank30 for storage.

The water purifying region may have capability for pollution watertreatment 40, which may include conventional mechanical, chemical and/orbiological cleansing treatments. For instance, such treatments may occurwithin a basin or vessel having an area containing aerobic and anaerobicbacteria (for biological treatment), an area containing cationic,anionic, and/or non-ionic polyelectrolyte flocculants (chemicaltreatment) and an area containing a clarifier 50 (mechanical treatment)that allows waste particulate matter to settle. A recirculating pump 60may be used to recirculate the wastewater in the pollution watertreatment 40. It may pump excess sludge to a sludge silo 70 for storageduring times when there is an ample supply of fresh sludge in wastewaterto sustain aerobic and anaerobic bacteria. It may pump sludge back tothe pollution water treatment 40 from the sludge silo 70 if needed tosustain the anaerobic or aerobic bacteria during times when the amountof sludge in fresh wastewater is less than that necessary to sustain theaerobic or anaerobic bacteria. Such times are determined based uponwhether fresh supplies of the wastewater alone contain sufficientquantities of contaminants for the bacteria to feed upon.

Thus, fluctuations in wastewater demand over time may be compensated tosustain the bacteria. Excess contaminants (sludge) that are beyond whatis needed to sustain the bacteria population at current levels areextracted. Some portion of the excess is pumped back at a later timewhen the amount of contaminants in the wastewater is less than what thebacteria population needs to sustain itself at current levels. Such anability prevents unwanted expansion of the bacteria population duringpeak demand times beyond what can't be sustained for long and prevents asudden drop in the bacteria population at other times. The sludgeextraction may be performed by mechanical techniques, which are cheaperto use than chemical or biological techniques.

The sludge drying region includes a sludge drying network 80 that driesthe excess sludge from the sludge silo 70 and discharges the driedsludge to a stocking tank 90. A blender 100 is provided to blendtogether grease from the grease tank 30, dried sludge from the stockingtank 90 and biomass leftovers 110. The biomass leftovers may bepulverulent wood charcoal, pulverulent cellulose, vegetable oil,vegetable alcohol, or any combination thereof. Vegetable alcohol refersto ethanol alcohol, methanol alcohol, a combination of each, or otherforms of alcohol derived from vegetable oil after undergoingtransesterification.

The power generating region may be considered to have two aspects. Thefirst includes an incinerator 120 that burns the mixture from theblender 100 to transform water into steam to drive a steam turbine 130having an electric generator to generate electricity as the steamturbine is driven. The second includes a sand filter 140 that filterswater leaving the purifying region and includes a water turbine 150driven by the filtered, purified water to generate electricity with anelectric generator that generates the electricity as the water turbineis driven. The water discharging through the water turbine may enter adischarging region to be further treated with a conventional ultraviolettreatment 160, depending upon whether the water is to be drinkable orused for agricultural purposes. If the water is merely be to dischargedback into the same stream that the lifting pump 10 diverted the waterinitially, then the ultraviolet treatment 160 may not be needed.

While the foregoing description and drawings represent the preferredembodiments of the present invention, it will be understood that variouschanges and modifications may be made without departing from the scopeof the present invention.

1. A method of energy production while cleansing wastewater ofcontaminants, comprising cleansing wastewater of contaminants byextracting the contaminants from wastewater that render the wastewaterunhealthy for human consumption, the contaminants including sludge andincluding at least one of grease and fats; and realizing energyproduction by forming a fuel source, the fuel source being formed fromdrying the extracted sludge, and blending together the at least one ofgrease and fats, the dried sludge and biomass leftovers, the biomassleftovers being selected from a group consisting of pulverulent woodcharcoal, pulverulent sawdust, pulverulent cellulosic materials,vegetable oil, vegetable alcohol, and any combination thereof.
 2. Amethod of claim 1, wherein the realizing of the energy productionincludes burning the fuel source to produce heat.
 3. A method of claim2, wherein the realizing of the energy production includes driving asteam turbine with the produced heat to generate power.
 4. A method ofclaim 1, further comprising cleansing the wastewater with a treatmentprocess selected from a group consisting of a mechanical treatmentprocess, a chemical treatment process, a biological treatment processesand any combination thereof, and filtering the cleansed wastewater.
 5. Amethod of claim 4, wherein the realizing of the energy productionincludes driving a water turbine with the filtered, cleansed wastewaterto generate power.
 6. A method of claim 5, wherein the realizing of theenergy production further includes burning the fuel source, transformingwater into steam with heat generated from the burning of the fuelsource, driving a steam turbine with the steam to generate furtherpower.
 7. A method of claim 6, wherein the realizing of the energyproducuon further includes converting the power and the further powerinto electricity.
 8. A method of claim 1, further comprisingcompensating for changes in wastewater demand by using a population ofbacteria to digest additional contaminants in the wastewater;determining whether fresh supplies of the wastewater alone aresufficient to sustain the population of the bacteria with sufficientquantities of the contaminants to feed upon and, if not supplementingthe fresh supplies of the wastewater with the extracted sludge.
 9. Amethod of claim 8, further comprising ceasing the extracting of thesludge while supplementing the fresh supplies of the wastewater with theextracted sludge.
 10. A method of claim 9, further comprising resumingthe extracting of the sludge after ceasing the supplementing when thedetermining finds that the fresh supplies of the wastewater alone havebecome sufficient to sustain the bacteria with sufficient quantities ofthe contaminants to feed upon.
 11. A fuel source for energy production,comprising a blend of biomass leftovers and extracted wastewatercontaminants that render the wastewater unhealthy for human consumption,the contaminants includling dried sludge and including at least one ofgrease and fats; the biomass leftovers being selected from a groupconsisting of pulverulent wood charcoal, pulverulent sawdust,pulverulent cellulosic materials, vegetable oil, vegetable alcohol, andany combination thereof, the blend forming a fuel source that iscombustible to burn.